Search Results (1,917)

This review explores the current status of green hydrogen integration into energy and industrial ecosystems. By considering notable examples of existing and developing green hydrogen initiatives, combined with insights from the relevant scientific literature, this paper illustrates the practical implementation of those systems according to their main end use: power and heat generation, mobility, industry, or their combination. Main patterns are highlighted in terms of sectoral applications, geographical distribution, development scales, storage solutions, electrolyzer technology, grid interaction, and financial viability. Open challenges are also addressed, including the high production costs, an underdeveloped transport and distribution infrastructure, the geopolitical aspects and the weak business models, with the industrial sector appearing as the most favorable environment where such challenges may first be overcome in the medium term. Full article

Graphene/h-BN/Si heterostructures show considerable potential for future use in infrared detection and photovoltaic technologies due to their adjustable electrical behavior and well-matched interfacial structure. The near-lattice match between graphene and hexagonal boron nitride (h-BN) enables the deposition of low-defect-density graphene on h-BN surfaces. This study presents a thorough exploration of the low-frequency electrical noise behavior of graphene/h-BN/Si heterojunctions under both forward and reverse bias conditions at room temperature. Graphene nanolayers were directly grown on h-BN films using microwave plasma-enhanced CVD. The h-BN layers were formed by reactive high-power impulse magnetron sputtering (HIPIMS). Four h-BN thicknesses were examined: 1 nm, 3 nm, 5 nm, and 15 nm. A reference graphene/Si junction (without h-BN) prepared under identical synthesis conditions was also studied for comparison. Low-frequency noise analysis enabled the identification of dominant charge transport mechanisms in the different device structures. Our results demonstrate that grain boundaries act as dominant defects contributing to increased noise intensity under high forward bias. Statistical analysis of voltage noise spectral density across multiple samples, supported by Raman spectroscopy, reveals that hydrogen-related defects significantly contribute to 1/f noise in the linear region of the junction’s current–voltage characteristics. This study provides the first in-depth insight into the impact of h-BN interlayers on low-frequency noise in graphene/Si heterojunctions. Full article

Hydrogen-induced steel embrittlement imposes a technical difficulty in facilitating effective and safe hydrogen transportation via pipelines. This investigative study assesses the potency of polyvinylidene fluoride (PVDF)–graphene-based composite coatings in the inhibition of hydrogen permeation. Spin coating was the method selected for this study, and varying graphene concentrations ranging from 0.1 to 1wt% were selected and applied to 306 stainless steel substrates. A membrane permeation cell was used in the evaluation of hydrogen permeability, while the impact of graphene loading on coating performance was analyzed using the response surface methodology (RSM). The outcomes showed an inversely proportional relationship between the graphene concentration and hydrogen ingress. The permeation coefficient for pure PVDF was recorded as 16.74, which decreased to 14.23, 12.10, and 11.46 for 0.3, 0.5, and 1.0 wt% PVDF-G, respectively, with the maximum reduction of 31.6% observed at 1.0 wt%. ANOVA established statistical significance, along with indications of strong projection dependability. However, the inhibition reduction stabilized with increasing graphene concentrations, likely caused by nanoparticle agglomeration. The results support the notion of PVDF–graphene’s potential as a suitable coating for the transformation of pipelines for hydrogen transport infrastructure. This research will aid in the establishment of suitable contemporary barrier coating materials, which will enable the safe utilization of hydrogen energy in the current energy transportation grid. Full article

This review article provides an overview of the use of hydrogen and tyre pyrolysis oil as fuels for homogeneous charge compression ignition (HCCI) engines. It discusses their properties, the ways they are produced and their sustainability, which is of particular importance in the present moment. Both fuels have certain advantages but also throw up many challenges, which complicate their application in HCCI engines. The paper scrutinises engine performance with hydrogen and tyre pyrolysis oil, respectively, and compares the fuels’ emissions, a crucial focus from an environmental perspective. It also surveys related technologies that have recently emerged, their effects and environmental impacts, and the rules and regulations that are starting to become established in these areas. Furthermore, it provides a comparative discussion of various engine performance data in terms of combustion behaviour, emission levels, fuel economy and potential costs or savings in real terms. The analysis reveals significant research gaps, and recommendations are provided as to areas for future study. The paper argues that hydrogen and tyre pyrolysis oil might sometimes be used together or in complementary ways to benefit HCCI engine performance. The importance of life-cycle assessment is noted, acknowledging also the requirements of the circular economy. The major findings are summarised with some comments on future perspectives for the use of sustainable fuels in HCCI engines. This review article provides a helpful reference for researchers working in this area and for policymakers concerned with establishing relevant legal frameworks, as well as for companies in the sustainable transport sector. Full article

The global energy transition is accelerating, yet new and underestimated challenges have emerged since 2024. Rising electricity demand—driven by artificial intelligence data centres, extreme heatwaves, and the electrification of transport—has exceeded earlier projections and shifted the system’s pressure point from generation to flexibility. At the same time, an oversupply of solar PV panels and lithium-ion batteries is lowering costs but increasing the risk of trade conflicts and supply chain concentration. This article presents a meta-analysis of 12 energy scenarios from 2024 to 2025, based on institutional outlooks (IEA, BNEF, and WEF) and peer-reviewed publications selected using transparent quality criteria (TRL thresholds, JRC guidance, and data transparency). A difference-in-differences method is applied to identify changes between editions. Results show a demand increase of over 2200 TWh by 2035, a decline in the “Net-Zero premium” from 19% to 15%, and a pressing need to redirect investment from gas infrastructure to grids, storage, and hydrogen. A case study for Central and Eastern Europe reveals that Poland will require USD 5–6 billion annually, primarily for transmission networks. These findings support a capital shift toward resilient and socially acceptable decarbonisation pathways. Full article

The Middle East and North Africa region has not played a major role in climate action so far, and several countries depend economically on fossil fuel exports. However, this is a region with vast solar energy resources, which can be exploited affordably for power generation and hydrogen production at scale to eventually reach carbon neutrality. In this paper, we elaborate on the case of the United Arab Emirates and explore the aspirations and feasibility of its net-zero by 2050 target. While we affirm the concept per se, we also highlight the technological complexity and economic dimensions that accompany such transformation. We expect the UAE’s electricity demand to triple between today and 2050, and the annual green hydrogen production is expected to reach 3.5 Mt, accounting for over 40% of the electricity consumption. Green hydrogen will provide power-to-fuel solutions for aviation, maritime transport and hard-to-abate industries. At the same time, electrification will intensify—most importantly in road transport and low-temperature heat demands. The UAE can meet its future electricity demands primarily with solar power, followed by natural gas power plants with carbon capture, utilization and storage, while the role of nuclear power in the long term is unclear at this stage. Full article

Liquid Organic Hydrogen Carriers (LOHCs) represent a promising technology for the safe storage and transport of hydrogen. Its technical development largely depends on the catalysts used in the hydrogenation and dehydrogenation processes. Typically, noble metal-based monometallic catalysts are employed, although they present limitations in terms of cost and availability. This study uses the DBT system to explore the potential of nickel (Ni) as a catalytic alternative. In dehydrogenation, its role as an additive in low-loaded Pt-based catalysts (0.25 wt%) was evaluated, showing a significant increase in activity, with dehydrogenation levels exceeding 95%, compared to 82% obtained with monometallic Pt catalysts. This improvement is attributed to the formation of Pt-Ni alloys. On the other hand, although the bimetallic systems were not effective in hydrogenation, a commercial Ni/Al₂O₃-SiO₂ catalyst was tested, achieving hydrogenation degrees of 80% in just 40 min, after pressure and catalyst loading optimization. These results position Ni as a key component in LOHC catalysis, either as an effective additive in Pt-based systems or as an active metal itself, due to its excellent performance and low cost. This paves the way for economically viable and efficient catalytic solutions for hydrogen storage applications, bridging the gap between performance and practicality. Full article

This article provides an overview of current hydrogen technologies used in road transport, with particular emphasis on their potential for decarbonizing the mobility sector. The author analyzes both fuel cells and hydrogen combustion in internal combustion engines as two competing approaches to using hydrogen as a fuel. He points out that although fuel cells offer higher efficiency, hydrogen combustion technologies can be implemented more quickly because of their compatibility with existing drive systems. The article emphasizes the importance of hydrogen’s source—so-called green hydrogen produced from renewable energy sources has the greatest ecological potential. Issues related to the storage, distribution, and safety of hydrogen use in transport are also analyzed. The author also presents the current state of refueling infrastructure and forecasts for its development in selected countries until 2030. He points to the need to harmonize legal regulations and to support the development of hydrogen technologies at the national and international levels. He also highlights the need to integrate the energy and transport sectors to effectively utilize hydrogen as an energy carrier. The article presents a comprehensive analysis of technologies, policies, and markets, identifying hydrogen as a key link in the energy transition. In conclusion, the author emphasizes that the future of hydrogen transport depends not only on technical innovations, but above all on coherent strategic actions and infrastructure investments. Full article

Hydrogen energy is valued for its diverse sources and clean, low-carbon nature and is a promising secondary energy source with wide-ranging applications and a significant role in the global energy transition. Nonetheless, hydrogen’s low energy density makes its large-scale storage and transport challenging. Liquid hydrogen, with its high energy density and easier transport, offers a practical solution. This study examines the global hydrogen liquefaction methods, with a particular emphasis on the liquid nitrogen pre-cooling Claude cycle process. It also examines the factors in the helium refrigeration cycle—such as the helium compressor inlet temperature, outlet pressure, and mass—that affect energy consumption in this process. Using HYSYS software, the hydrogen liquefaction process is simulated, and a complete process system is developed. Based on theoretical principles, this study explores the pre-cooling, refrigeration, and normal-to-secondary hydrogen conversion processes. By calculating and analyzing the process’s energy consumption, an optimized flow scheme for hydrogen liquefaction is proposed to reduce the total power used by energy equipment. The study shows that the hydrogen mass flow rate and key helium cycle parameters—like the compressor inlet temperature, outlet pressure, and flow rate—mainly affect energy consumption. By optimizing these parameters, notable decreases in both the total and specific energy consumption were attained. The total energy consumption dropped by 7.266% from the initial 714.3 kW, and the specific energy consumption was reduced by 11.94% from 11.338 kWh/kg. Full article

This paper presents a novel literature survey on leveraging electrolysis for grid frequency stabilization in power systems with high penetration of renewable energy sources (RESs), uniquely integrating global research findings with specific insights into the Polish energy context—a region facing acute grid challenges due to rapid RES growth and infrastructure limitations. The intermittent nature of wind and solar power exacerbates frequency fluctuations, necessitating dynamic demand-side management solutions like hydrogen production via electrolysis. By synthesizing over 30 studies, the survey reveals key results: electrolysis systems, particularly PEM and alkaline electrolyzers, can reduce frequency deviations by up to 50% through fast frequency response (FFR) and primary reserve provision, as demonstrated in simulations and real-world pilots (e.g., in France and the Netherlands); however, economic viability requires enhanced compensation schemes, with current models showing unprofitability without subsidies. Technological advancements, such as transistor-based rectifiers, improve efficiency under partial loads, while integration with RES farms mitigates overproduction issues, as evidenced by Polish cases where 44 GWh of solar energy was curtailed in March 2024. The survey contributes actionable insights for policymakers and engineers, including recommendations for deploying electrolyzers to enhance grid resilience, support hydrogen-based transportation, and facilitate Poland’s target of 50.1% RESs by 2030, thereby advancing the green energy transition amid rising instability risks like blackouts in RES-heavy systems. Full article

Hydrogen energy is considered a crucial clean energy carrier for replacing fossil fuels in the future. Liquid hydrogen (LH₂), with its economic advantages and high purity, is central to the development of future hydrogen refueling stations (HRSs). However, leakage poses significant fire and explosion risks, challenging its safe industrial use. In this study, a numerical model of LH₂ leakage at an HRS in Chongqing was established using Computational Fluid Dynamics (CFD) software. The diffusion law of a flammable gas cloud (FGC) was examined under the synergistic effect of the leakage direction, rate, and wind speed of an LH₂ storage tank in an HRS. The phase transition of LH₂ presents dual risks of combustion and frostbite owing to the spatial overlap between low-temperature areas and FGCs. The findings revealed that the equivalent stoichiometric gas cloud volume (Q9) reached 685 m³ in the case of crosswind leakage, with the superimposed effect of reflected waves from the LH₂ transport vehicle resulting in a peak explosion overpressure of 0.61 bar. The low-temperature hazard area and the FGC (with a concentration of 30–75%) show significant spatial overlap. These research outcomes offer crucial theoretical underpinning for enhancing equipment layout optimization and safety protection strategies at HRSs. Full article

Mixing hydrogen into natural gas pipelines for transportation is an effective solution to the imbalance between the supply and demand of hydrogen energy. Studying the influence of bent pipes in hydrogen-mixed natural gas explosion accidents can enhance the safety of hydrogen energy storage and transportation. Through experiments and LES, the influence of pipe spacing configuration on the vented explosion of this mixed gas in pipes with a large length-to-diameter ratio was analyzed. The maximum explosion pressure (Pmax) of the straight pipe is 21.7 kPa and the maximum pressure rise rate ((dp/dt)max) is 1.8 MPa/s. After adding the double elbow, Pmax increased to 65.2 kPa and (dp/dt)max increased to 3.7 MPa/s. By increasing the distance (D1) from bent pipe-1 to the ignition source, the flame shape changes from “finger-shaped” to “concave-shaped” to “wrinkled-shaped.” When D1 is at its minimum, the explosion reaction is the most intense. However, as D1 increases, each characteristic parameter decreases linearly and the flame propagation speed significantly reduces, the flame area decays more severely, and the flame acceleration effect is also suppressed. When the distance between the two bent pipes (D2) was gradually increased, the flame transformed from “finger-shaped” to “tongue-shaped” to “wrinkled-shaped”. The flame area curve exhibited a unique evolutionary process of “hitting bottom” to “rebounding” to “large-scale flame backflow”. This paper explores the development process of various characteristic parameters, which is of great reference value for preventing explosions in hydrogen-blended natural gas pipelines in underground pipe galleries. Full article

The thermal insulation performance of liquid hydrogen (LH₂) storage tanks is critical for long-distance transportation. The active cooled shield (ACS) technologies, such as the liquid nitrogen cooled shield (LNCS) and the vapor hydrogen cooled shield (VHVCS) are important thermal insulation methods. Many researchers installed the VHVCS inside the multilayer insulation (MLI) and obtained the optimal position. However, the MLI layer is often thinner than the vacuum interlayer between the inner and outer tanks, and there is a large vacuum interlayer between the outermost side of MLI and the inner wall of the outer tank. It is unknown whether the insulation performance can be improved if we install ACS in the mentioned vacuum interlayer and separate a portion of the MLI to be installed on the outer surface of ACS. In this configuration, the number of inner MLI (IMLI) layers and the ACS position are interdependent, a coupling that has not been thoroughly investigated. Therefore, thermodynamic models for MLI, MLI-LNCS, and MLI-VHVCS schemes were developed based on the Layer-by-Layer method. By applying Robin boundary conditions, the temperature distribution and heat leakage of the MLI scheme were predicted. Considering the coupled effects of IMLI layer count and ACS position, a co-optimization strategy was adopted, based on an alternating iterative search algorithm. The results indicate that for the MLI-LNCS scheme, the optimal number of IMLI layers and LNCS position are 36 layers and 49%, respectively. For the MLI-VHVCS scheme, the optimal values are 21 layers and 39%, respectively. Compared to conventional MLI, the MLI-LNCS scheme achieves an 88.09% reduction in heat leakage. However, this improvement involves increased system complexity and higher operational costs from LN₂ circulation. In contrast, the MLI-VHVCS scheme achieves a 62.74% reduction in heat leakage, demonstrating that using sensible heat from cryogenic vapor can significantly improve the thermal insulation performance of LH₂ storage tanks. The work of this paper provides a reference for the design and optimization of the insulation scheme of LH₂ storage tanks. Full article

In this study, a 3D model is developed to simulate multi-hole leakage scenarios in buried pipelines transporting hydrogen-blended natural gas (HBNG). By introducing three parameters—the First Dangerous Time (FDT), Ground Dangerous Range (GDR), and Farthest Dangerous Distance (FDD)—to characterize the diffusion hazard of the gas mixture, this study further analyzes the effects of the number of leakage holes, hole spacing, hydrogen blending ratio (HBR), and soil porosity on the diffusion hazard of the gas mixture during leakage. Results indicate that gas leakage exhibits three distinct phases: initial independent diffusion, followed by an intersecting accelerated diffusion stage, and culminating in a unified-source diffusion. Hydrogen exhibits the first two phases, whereas methane undergoes all three and dominates the GDR. Concentration gradients for multi-hole leakage demonstrate similarities to single-hole scenarios, but multi-hole leakage presents significantly higher hazards. When the inter-hole spacing is small, diffusion characteristics converge with those of single-hole leakage. Increasing HBR only affects the gas concentration distribution near the leakage hole, with minimal impact on the overall ground danger evolution. Conversely, variations in soil porosity substantially impact leakage-induced hazards. The outcomes of this study will support leakage monitoring and emergency management of HBNG pipelines. Full article

With the deepening electrification of transportation, hydrogen fuel cell electric vehicles (FCEVs) are emerging as a vital component of clean and electrified transportation systems. Nonetheless, renewable-based hydrogen production–refueling stations (HPRSs) for FCEVs still need solid models for accurate simulations and a practical capacity optimization method for cost reduction. To address this gap, this study leverages real operation data from China’s largest HPRS to establish and validate a comprehensive model integrating hydrogen production, storage, renewables, FCEVs, and the power grid. Building on this validated model, a novel capacity optimization framework is proposed, incorporating an improved Jellyfish Search Algorithm (JSA) to minimize the initial investment cost, operating cost, and levelized cost of hydrogen (LCOH). The results demonstrate the framework’s significant innovations and effectiveness: It achieves the maximum reductions of 29.31% in the initial investment, 100% in the annual operational cost, and 44.19% in LCOH while meeting FCEV demand. Simultaneously, it reduces peak grid load by up to 43.80% and enables renewable energy to cover up to 89.30% of transportation hydrogen demand. This study contributes to enhancing economic performance and optimizing the design and planning of HPRS for FCEVs, as well as promoting sustainable transportation electrification. Full article